Steam-engine.



No. 636,929. Patented Nov. l4, I899.

J. H.'STBEET. STEAM Enema.

(Application filed June 17, 1899.)

(No Model.)

2 Sheets-Shae: l,

[III/l/I/A THEN No. 636,929. Patented Nov. l4, I899.

J. H STREET. STEAM ENGINE.

(ApgXica-tion filed June 17,1899.) (No Model.) 2 Sheets-Shunt 2.

UNITED STATES PATENT OFFICE.

JOHN HADFIELD STREET, RUGBY, ENGLAND, ASSIGN OR TO THE WILLANS & ROBINSON, LIMITED, OF SAME PLACE.

STEAM-ENGINE.

SPECIFICATION forming part of Letters Patent N 0. 636,929, dated November 14, 1899. Application filed June 17, 1899- Serial No. 720,937. (N0 model.)

To all whom it may concern.-

Be it known that I,JOHN HADFIELD STREET, engineer, asubject of the Queen of Great Britain, residing at Victoria Works, Rugby, in the county of Warwick, England, have invented certain new and useful Improvements in Steam-Engines, of which the following is a specification.

This invention relates to central-valve engines of the type known as the Willans engine, in which steam is admitted to the cylinder, if there be only one over each crank,v or to the upper cylinder, if there be more than one, by a separate admission-Valve independ ent of the central valve; and the invention has for its object a particular arrangement of the central valve and of the hollow piston-rod which makes it unnecessary to carry the hollow piston-rod through the end of the cylinder into the steam-chest, as would otherwise have to be done in order to obtain a sufficient pressure upon the line of valves to insure their being held down in constant thrust notwithstanding the effect of inertia upon them.

In the accompanying drawings, Figure .1 shows a longitudinal central section of the upper part of the engine, and Fig. 2 is a similar section taken at right angles to the section shown in Fig. 1.

A is the upper cylinder, 13 the piston in it, and O the hollow piston-rod, all of the usual type.

The upper piston o of the line of pistonvalves (which serves as an exhaust-valve only) is formed with a Very deep hollow body, into which enters a trunk 11, depending centrally from the cylinder-cover c and working steamtight'in the hollow valve-body by means of a gland or packing-rings d or otherwise. The parts are so proportioned that when the valve a is at the lowest part of its stroke the hanging trunk 19 still enters the gland or packingrings (1. The hanging trunk b communicates by a hole or port I) at its top with a steamchest e in or above the cylinder-cover c, which maybe covered by a valve f, which alternately opens and closes communication. The valve opens at an appropriate point in the upstroke of the central valve to cushion the latter toward the end of its upstroke and closes at an appropriate point upon the downstroke.

In cases where a rotating admission-valve is used, as shown in the drawings, such as is described in another application of this date made by me and filed June 17, 1899, Serial No. 720,936, the admission and cut off of the steam-supply to the hanging trunk can be effected by a port in such valve appropriately placed and shaped. Any suitable usual type of admission-valve'may be employed-as, for instance, a common fiat reciprocating gridvalveand that shown has been employed merely as an illustration of a suitable valve in order that the drawings might sufiiciently disclose a complete organization. It forms no part of the present invention and is claimed in my application above mentioned.

It is not essential that steam be alternately admitted to and cut off from the inside of the hanging trunk b and of the hollow piston-val ve body. Those spaces may be in permanent communication with the steam-chest e, in which case the downward pressure on the line of piston-valves is constant. By making the supply of steam intermittent the downward pressure can be removed or lessened at times when it is not required, and the pressure can, if necessary, be raised at certain times above that in the steam-chest by compression of the steam in the hollow valve-body as the latter rises.

What I claim is- 1. The combination of a cylinder, a cylinder-cover, a piston in the cylinder, a hollow piston-rod fixed to the piston, Valve-ports in the sides of the hollow piston-rod where it projects from the piston, a to-and-fro-reci.p= rocating piston-valve in the rod, a hollow trunk inside the piston-valve and fixed to the cylinder-cover and means for admitting steam to the hollow trunk.

2. The combination of a cylinder, a cylin= der-cover, a piston in the cylinder, a hollow piston-rod fixed to the piston, valve-ports in the sides of the hollow piston-rod where it projects from the piston, a to and-fro-reciprocating piston-valve in the rod, a hollow der-cover, a steam-chest, a piston in the cylinder, a hollow piston-rod fixed to the piston,

valve-ports in the sides of the hollow pistonrod where it projects from the piston, a toand-fro-reciprocating piston-valve in the rod, a hollow trunk inside the piston-valve and fixed to the cylinder-cover and a valve for admitting steam from the steam-chest to the hollow trunk.

JOHN HADFIELD STREET.

\Vitnesses:

WILFRED CARPMAEL, WALTER J. SKERTEN. 

